Local officials have collected damage reports from residents to determine where the hardest-hit areas are, said IEMA spokeswoman Patti Thompson. Based on those results, assessment teams will visit neighborhoods where flood waters destroyed basements and wrecked carpet and drywall.

Once assessors with the state-level agency believe they have substantial evidence for declaring a federal disaster area, they'll send their results to the Federal Emergency Management Agency for review. With every disaster, the threshold is different, Thompson said. Sometimes they need 200 destroyed homes, sometimes 800.

Reaching that number could happen after a handful of counties, or after all 48 that Gov. Pat Quinn has declared state disaster areas, are surveyed.

"If we get to the point when we think we have a substantial case and we get approved (by FEMA), we can always add other counties later," Thompson said.

Typically, FEMA will make a decision several weeks after the state agency's report is submitted, Thompson said. The process from today until then could be weeks, or months.

But that doesn't mean those affected by the flood shouldn't start fixing up.

"If they can, start making those repairs so they can get back into their home," Thompson said. "Just keep the receipts and have those, so if there is a federal disaster declaration, they'll have the documentation (to apply for federal grants or loans)."

Thompson also recommended taking pictures of damage and lost possessions.

As teams make their way across Cook, DuPage and Lake counties today, residents need not be home for assessors to rank their home based on how high the water levels appeared to have reached, Thompson said.

But if residents are home, they will be given the option to show the team the extent of the damage. The teams will rate homes on a scale of totally destroyed to light damage.

The individual assessments will ultimately have no bearing on homeowners' or businesses' ability to nab a federal grant or small interest loan down the line, because FEMA would conduct its own assessments. If FEMA declares a disaster area, individual property owners would then have to apply for aid.

The last time Illinois received federal aid for flooding was in 2010, after heavy July rains. FEMA gave residents and business owners about $320 million by the end of November that year.

Gov. Quinn spoke today about the flooding in the Albany Park neighborhood on Chicago's Northwest Side, where flooding from the North Branch of the Chicago River had water standing waist-deep in some parts of the neighborhood.

"We've never had, in our whole state of Illinois in its history since 1818, such a pervasive flood in so many different parts of Illinois," Quinn said.

Chicago-area home prices declined in January for the fifth consecutive month but remained 2.5 percent ahead of where they were a year earlier, according a barometer of the housing market's health, released Tuesday.